Women diagnosed with early breast cancer are now asked by their doctors to choose from a range of options for their preferred medical treatment plan. Little information is known about women's treatment decision-making and therefore nurses do not have evidence to guide this decision support. The aim of this descriptive survey was to investigate the prediagnostic decision-making behavior of a sample (N = 377) of Australian women, regarding their treatment choices for early breast cancer. The data were collected using the Pre-Decision Portfolio Questionnaire (PDPQ) by Pierce (1996), which includes the Michigan Assessment of Decision Styles (MADS). Of 366 participating women, 19.9% strongly agreed to all three items of the MADS factor Deferring Responsibility; 0.3% strongly agreed to all four factors of Avoidance; 32.7% strongly agreed on all four items of Information Seeking; and 63.4% strongly agreed to all five items of Deliberation. Women showed a variety of preferred decision styles, depending on age, education, occupation and employment status. Only 36% of women indicated it was critically important to "get the treatment over as soon as possible;" 55% to "participate in selecting treatment;" and 53% to "read a lot of information:" The understanding of factors that are important to women when they are making decisions for medical treatment is a mandatory step in designing customized evidence-based decision support, which can be delivered by nurses to help women during this distressing experience.